The present invention concerns devices for deviating structural cables, especially stays.
At present it is common to make structural cables as a bundle of individual stretched tendons anchored at their ends. The design of an construction work may involve diverting the cable in one or more areas of its path.
In stayed structures, the cables have an upper part situated near a tower and lower extremities anchored to the suspended structure, for example, the deck of a bridge. In a conventional design, the upper extremity of each cable is anchored to the tower. In other stayed structures, the cables follow paths whose general shape is that of an inverted V, and they are diverted to the tower by means of a device commonly referred to as a saddle.
At the saddle, the cable strands follow curved paths, typically with a substantially constant radius of curvature. Preferably, the tendons extend uninterruptedly along the saddle. Sufficient friction must be provided between the tendons and the saddle to avoid unwanted slippage.
WO 2007/121782 A1 discloses a saddle wherein each strand forming a tendon of the cable is received in an individual conduit whose wall presents, on either side of the plane containing the curved path of the strand, two inclined faces, giving the conduit a generally V-shaped cross-section. The V shape of the conduit's cross-section immobilizes the strand through a wedge effect whenever tension is applied to it by the load on the structure. This saddle design is not without its drawbacks. In particular, the contacts between the strand and the wall of its conduit are local, which is not favorable to good distribution of local stresses. Moreover, the saddle is not compatible with the use of individually sheathed strands because the individual sheath of a strand would be damaged by the pinching force brought about by the V shape of the conduit. Nonetheless, individually sheathed strands are frequently preferred for making structural cables because their corrosion resistance is enhanced by the insulation conferred by the sheath. If, however, use such strands with the saddle of WO 2007/121782 A1 is desired, the sheaths must be removed on the length of the strands placed inside the saddle, which requires the use of special measures to sufficiently insulate the metal of the strands. In spite of these measures, which can be complex and costly, stripping the tendons near the saddle risks introducing weakness into the anticorrosion protection of the stays.
An object of the present invention is to propose a different saddle design, which reduces the incidence of the aforementioned problems, in particular by ensuring adequate transmission of stresses within the curved path followed by the tendons.